Module chain 

The on-chain read boundary (SPEC §7, NC-9).

dig-store is network-free at its core (inherited from dig-merkle, INV-1): it never dials the chain itself. On-chain getters take a ChainSource the caller supplies — the user’s own verified node, or a trusted/threshold provider set — and prove every chain-anchored value against it before returning (NC-9). A single untrusted remote MUST NOT back a custody-grade read (NC-9 F1); the caller owns that trust decision.

The trait is the ONE canonical dig_chainsource_interface::ChainSource shared across the whole ecosystem — never a per-crate copy — re-exported here so a consumer reaching for the store getters finds the boundary in one place. Its coin_spend(coin_id) fail-closed lookup (Ok(None) = the coin is unspent/unknown; Err(_) = the source could not answer) is the primitive the store’s lineage walk composes.

Traits

ChainSource

A reads-only view of Chia chain state — the single canonical contract every provider implements and every consumer depends on.